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Subject[PATCH 08/11] blkcg: add request_queue->root_blkg
Date
With per-queue policy activation, root blkg creation will be moved to
blkcg core. Add q->root_blkg in preparation. For blk-throtl, this
replaces throtl_data->root_tg; however, cfq needs to keep
cfqd->root_group for !CONFIG_CFQ_GROUP_IOSCHED.

This is to prepare for per-queue policy activation and doesn't cause
any functional difference.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
---
block/blk-throttle.c | 16 ++++++++++------
block/cfq-iosched.c | 4 +++-
include/linux/blkdev.h | 2 ++
3 files changed, 15 insertions(+), 7 deletions(-)
diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 6f1bfdf..8c520fa 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -97,7 +97,6 @@ struct throtl_data
/* service tree for active throtl groups */
struct throtl_rb_root tg_service_tree;

- struct throtl_grp *root_tg;
struct request_queue *queue;

/* Total Number of queued bios on READ and WRITE lists */
@@ -131,6 +130,11 @@ static inline struct blkio_group *tg_to_blkg(struct throtl_grp *tg)
return pdata_to_blkg(tg);
}

+static inline struct throtl_grp *td_root_tg(struct throtl_data *td)
+{
+ return blkg_to_tg(td->queue->root_blkg);
+}
+
enum tg_state_flags {
THROTL_TG_FLAG_on_rr = 0, /* on round-robin busy list */
};
@@ -261,7 +265,7 @@ throtl_grp *throtl_lookup_tg(struct throtl_data *td, struct blkio_cgroup *blkcg)
* Avoid lookup in this case
*/
if (blkcg == &blkio_root_cgroup)
- return td->root_tg;
+ return td_root_tg(td);

return blkg_to_tg(blkg_lookup(blkcg, td->queue));
}
@@ -277,7 +281,7 @@ static struct throtl_grp *throtl_lookup_create_tg(struct throtl_data *td,
* Avoid lookup in this case
*/
if (blkcg == &blkio_root_cgroup) {
- tg = td->root_tg;
+ tg = td_root_tg(td);
} else {
struct blkio_group *blkg;

@@ -287,7 +291,7 @@ static struct throtl_grp *throtl_lookup_create_tg(struct throtl_data *td,
if (!IS_ERR(blkg))
tg = blkg_to_tg(blkg);
else if (!blk_queue_dead(q))
- tg = td->root_tg;
+ tg = td_root_tg(td);
}

return tg;
@@ -1245,12 +1249,12 @@ int blk_throtl_init(struct request_queue *q)

blkg = blkg_lookup_create(&blkio_root_cgroup, q, true);
if (!IS_ERR(blkg))
- td->root_tg = blkg_to_tg(blkg);
+ q->root_blkg = blkg;

spin_unlock_irq(q->queue_lock);
rcu_read_unlock();

- if (!td->root_tg) {
+ if (!q->root_blkg) {
kfree(td);
return -ENOMEM;
}
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index de95f9a..86440e0 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -3964,8 +3964,10 @@ static int cfq_init_queue(struct request_queue *q)
spin_lock_irq(q->queue_lock);

blkg = blkg_lookup_create(&blkio_root_cgroup, q, true);
- if (!IS_ERR(blkg))
+ if (!IS_ERR(blkg)) {
+ q->root_blkg = blkg;
cfqd->root_group = blkg_to_cfqg(blkg);
+ }

spin_unlock_irq(q->queue_lock);
rcu_read_unlock();
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index d2c69f8..b01c377 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -31,6 +31,7 @@ struct blk_trace;
struct request;
struct sg_io_hdr;
struct bsg_job;
+struct blkio_group;

#define BLKDEV_MIN_RQ 4
#define BLKDEV_MAX_RQ 128 /* Default maximum */
@@ -369,6 +370,7 @@ struct request_queue {

struct list_head icq_list;
#ifdef CONFIG_BLK_CGROUP
+ struct blkio_group *root_blkg;
struct list_head blkg_list;
#endif

--
1.7.7.3


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